sql: add the Bikeshare example according to English doc#937

Merged

zz-jason merged 3 commits intopingcap:masterfrom zz-jason:dev/explain-example

Nov 21, 2018

+45-6

Commits on Oct 22, 2018

add example according to the english version of the document
zz-jason
committed

Commits on Nov 21, 2018